/*
 * Copyright (c) 2016 Citrix Systems Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Softare Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#define XEN_NETIF_DEFINE_TOEPLITZ

#include "common.h"
#include <linux/vmalloc.h>
#include <linux/rculist.h>

static void xenvif_add_hash(struct xenvif *vif, const u8 *tag,
			    unsigned int len, u32 val)
{
	struct xenvif_hash_cache_entry *new, *entry, *oldest;
	unsigned long flags;
	bool found;

	new = kmalloc(sizeof(*entry), GFP_ATOMIC);
	if (!new)
		return;

	memcpy(new->tag, tag, len);
	new->len = len;
	new->val = val;

	spin_lock_irqsave(&vif->hash.cache.lock, flags);

	found = false;
	oldest = NULL;
	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
		/* Make sure we don't add duplicate entries */
		if (entry->len == len &&
		    memcmp(entry->tag, tag, len) == 0)
			found = true;
		if (!oldest || entry->seq < oldest->seq)
			oldest = entry;
	}

	if (!found) {
		new->seq = atomic_inc_return(&vif->hash.cache.seq);
		list_add_rcu(&new->link, &vif->hash.cache.list);

		if (++vif->hash.cache.count > xenvif_hash_cache_size) {
			list_del_rcu(&oldest->link);
			vif->hash.cache.count--;
			kfree_rcu(oldest, rcu);
		}
	}

	spin_unlock_irqrestore(&vif->hash.cache.lock, flags);

	if (found)
		kfree(new);
}

static u32 xenvif_new_hash(struct xenvif *vif, const u8 *data,
			   unsigned int len)
{
	u32 val;

	val = xen_netif_toeplitz_hash(vif->hash.key,
				      sizeof(vif->hash.key),
				      data, len);

	if (xenvif_hash_cache_size != 0)
		xenvif_add_hash(vif, data, len, val);

	return val;
}

static void xenvif_flush_hash(struct xenvif *vif)
{
	struct xenvif_hash_cache_entry *entry;
	unsigned long flags;

	if (xenvif_hash_cache_size == 0)
		return;

	spin_lock_irqsave(&vif->hash.cache.lock, flags);

	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
		list_del_rcu(&entry->link);
		vif->hash.cache.count--;
		kfree_rcu(entry, rcu);
	}

	spin_unlock_irqrestore(&vif->hash.cache.lock, flags);
}

static u32 xenvif_find_hash(struct xenvif *vif, const u8 *data,
			    unsigned int len)
{
	struct xenvif_hash_cache_entry *entry;
	u32 val;
	bool found;

	if (len >= XEN_NETBK_HASH_TAG_SIZE)
		return 0;

	if (xenvif_hash_cache_size == 0)
		return xenvif_new_hash(vif, data, len);

	rcu_read_lock();

	found = false;

	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
		if (entry->len == len &&
		    memcmp(entry->tag, data, len) == 0) {
			val = entry->val;
			entry->seq = atomic_inc_return(&vif->hash.cache.seq);
			found = true;
			break;
		}
	}

	rcu_read_unlock();

	if (!found)
		val = xenvif_new_hash(vif, data, len);

	return val;
}

void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb)
{
	struct flow_keys flow;
	u32 hash = 0;
	enum pkt_hash_types type = PKT_HASH_TYPE_NONE;
	u32 flags = vif->hash.flags;
	bool has_tcp_hdr;

	/* Quick rejection test: If the network protocol doesn't
	 * correspond to any enabled hash type then there's no point
	 * in parsing the packet header.
	 */
	switch (skb->protocol) {
	case htons(ETH_P_IP):
		if (flags & (XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
			     XEN_NETIF_CTRL_HASH_TYPE_IPV4))
			break;

		goto done;

	case htons(ETH_P_IPV6):
		if (flags & (XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP |
			     XEN_NETIF_CTRL_HASH_TYPE_IPV6))
			break;

		goto done;

	default:
		goto done;
	}

	memset(&flow, 0, sizeof(flow));
	if (!skb_flow_dissect_flow_keys(skb, &flow, 0))
		goto done;

	has_tcp_hdr = (flow.basic.ip_proto == IPPROTO_TCP) &&
		      !(flow.control.flags & FLOW_DIS_IS_FRAGMENT);

	switch (skb->protocol) {
	case htons(ETH_P_IP):
		if (has_tcp_hdr &&
		    (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP)) {
			u8 data[12];

			memcpy(&data[0], &flow.addrs.v4addrs.src, 4);
			memcpy(&data[4], &flow.addrs.v4addrs.dst, 4);
			memcpy(&data[8], &flow.ports.src, 2);
			memcpy(&data[10], &flow.ports.dst, 2);

			hash = xenvif_find_hash(vif, data, sizeof(data));
			type = PKT_HASH_TYPE_L4;
		} else if (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4) {
			u8 data[8];

			memcpy(&data[0], &flow.addrs.v4addrs.src, 4);
			memcpy(&data[4], &flow.addrs.v4addrs.dst, 4);

			hash = xenvif_find_hash(vif, data, sizeof(data));
			type = PKT_HASH_TYPE_L3;
		}

		break;

	case htons(ETH_P_IPV6):
		if (has_tcp_hdr &&
		    (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP)) {
			u8 data[36];

			memcpy(&data[0], &flow.addrs.v6addrs.src, 16);
			memcpy(&data[16], &flow.addrs.v6addrs.dst, 16);
			memcpy(&data[32], &flow.ports.src, 2);
			memcpy(&data[34], &flow.ports.dst, 2);

			hash = xenvif_find_hash(vif, data, sizeof(data));
			type = PKT_HASH_TYPE_L4;
		} else if (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6) {
			u8 data[32];

			memcpy(&data[0], &flow.addrs.v6addrs.src, 16);
			memcpy(&data[16], &flow.addrs.v6addrs.dst, 16);

			hash = xenvif_find_hash(vif, data, sizeof(data));
			type = PKT_HASH_TYPE_L3;
		}

		break;
	}

done:
	if (type == PKT_HASH_TYPE_NONE)
		skb_clear_hash(skb);
	else
		__skb_set_sw_hash(skb, hash, type == PKT_HASH_TYPE_L4);
}

u32 xenvif_set_hash_alg(struct xenvif *vif, u32 alg)
{
	switch (alg) {
	case XEN_NETIF_CTRL_HASH_ALGORITHM_NONE:
	case XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ:
		break;

	default:
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
	}

	vif->hash.alg = alg;

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

u32 xenvif_get_hash_flags(struct xenvif *vif, u32 *flags)
{
	if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
		return XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED;

	*flags = XEN_NETIF_CTRL_HASH_TYPE_IPV4 |
		 XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
		 XEN_NETIF_CTRL_HASH_TYPE_IPV6 |
		 XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

u32 xenvif_set_hash_flags(struct xenvif *vif, u32 flags)
{
	if (flags & ~(XEN_NETIF_CTRL_HASH_TYPE_IPV4 |
		      XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
		      XEN_NETIF_CTRL_HASH_TYPE_IPV6 |
		      XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP))
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	vif->hash.flags = flags;

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

u32 xenvif_set_hash_key(struct xenvif *vif, u32 gref, u32 len)
{
	u8 *key = vif->hash.key;
	struct gnttab_copy copy_op = {
		.source.u.ref = gref,
		.source.domid = vif->domid,
		.dest.u.gmfn = virt_to_gfn(key),
		.dest.domid = DOMID_SELF,
		.dest.offset = xen_offset_in_page(key),
		.len = len,
		.flags = GNTCOPY_source_gref
	};

	if (len > XEN_NETBK_MAX_HASH_KEY_SIZE)
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	if (copy_op.len != 0) {
		gnttab_batch_copy(&copy_op, 1);

		if (copy_op.status != GNTST_okay)
			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
	}

	/* Clear any remaining key octets */
	if (len < XEN_NETBK_MAX_HASH_KEY_SIZE)
		memset(key + len, 0, XEN_NETBK_MAX_HASH_KEY_SIZE - len);

	xenvif_flush_hash(vif);

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size)
{
	if (size > XEN_NETBK_MAX_HASH_MAPPING_SIZE)
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	vif->hash.size = size;
	memset(vif->hash.mapping[vif->hash.mapping_sel], 0,
	       sizeof(u32) * size);

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
			    u32 off)
{
	u32 *mapping = vif->hash.mapping[!vif->hash.mapping_sel];
	unsigned int nr = 1;
	struct gnttab_copy copy_op[2] = {{
		.source.u.ref = gref,
		.source.domid = vif->domid,
		.dest.domid = DOMID_SELF,
		.len = len * sizeof(*mapping),
		.flags = GNTCOPY_source_gref
	}};

	if ((off + len < off) || (off + len > vif->hash.size) ||
	    len > XEN_PAGE_SIZE / sizeof(*mapping))
		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	copy_op[0].dest.u.gmfn = virt_to_gfn(mapping + off);
	copy_op[0].dest.offset = xen_offset_in_page(mapping + off);
	if (copy_op[0].dest.offset + copy_op[0].len > XEN_PAGE_SIZE) {
		copy_op[1] = copy_op[0];
		copy_op[1].source.offset = XEN_PAGE_SIZE - copy_op[0].dest.offset;
		copy_op[1].dest.u.gmfn = virt_to_gfn(mapping + off + len);
		copy_op[1].dest.offset = 0;
		copy_op[1].len = copy_op[0].len - copy_op[1].source.offset;
		copy_op[0].len = copy_op[1].source.offset;
		nr = 2;
	}

	memcpy(mapping, vif->hash.mapping[vif->hash.mapping_sel],
	       vif->hash.size * sizeof(*mapping));

	if (copy_op[0].len != 0) {
		gnttab_batch_copy(copy_op, nr);

		if (copy_op[0].status != GNTST_okay ||
		    copy_op[nr - 1].status != GNTST_okay)
			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
	}

	while (len-- != 0)
		if (mapping[off++] >= vif->num_queues)
			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;

	vif->hash.mapping_sel = !vif->hash.mapping_sel;

	return XEN_NETIF_CTRL_STATUS_SUCCESS;
}

#ifdef CONFIG_DEBUG_FS
void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m)
{
	unsigned int i;

	switch (vif->hash.alg) {
	case XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ:
		seq_puts(m, "Hash Algorithm: TOEPLITZ\n");
		break;

	case XEN_NETIF_CTRL_HASH_ALGORITHM_NONE:
		seq_puts(m, "Hash Algorithm: NONE\n");
		/* FALLTHRU */
	default:
		return;
	}

	if (vif->hash.flags) {
		seq_puts(m, "\nHash Flags:\n");

		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4)
			seq_puts(m, "- IPv4\n");
		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP)
			seq_puts(m, "- IPv4 + TCP\n");
		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6)
			seq_puts(m, "- IPv6\n");
		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP)
			seq_puts(m, "- IPv6 + TCP\n");
	}

	seq_puts(m, "\nHash Key:\n");

	for (i = 0; i < XEN_NETBK_MAX_HASH_KEY_SIZE; ) {
		unsigned int j, n;

		n = 8;
		if (i + n >= XEN_NETBK_MAX_HASH_KEY_SIZE)
			n = XEN_NETBK_MAX_HASH_KEY_SIZE - i;

		seq_printf(m, "[%2u - %2u]: ", i, i + n - 1);

		for (j = 0; j < n; j++, i++)
			seq_printf(m, "%02x ", vif->hash.key[i]);

		seq_puts(m, "\n");
	}

	if (vif->hash.size != 0) {
		const u32 *mapping = vif->hash.mapping[vif->hash.mapping_sel];

		seq_puts(m, "\nHash Mapping:\n");

		for (i = 0; i < vif->hash.size; ) {
			unsigned int j, n;

			n = 8;
			if (i + n >= vif->hash.size)
				n = vif->hash.size - i;

			seq_printf(m, "[%4u - %4u]: ", i, i + n - 1);

			for (j = 0; j < n; j++, i++)
				seq_printf(m, "%4u ", mapping[i]);

			seq_puts(m, "\n");
		}
	}
}
#endif /* CONFIG_DEBUG_FS */

void xenvif_init_hash(struct xenvif *vif)
{
	if (xenvif_hash_cache_size == 0)
		return;

	BUG_ON(vif->hash.cache.count);

	spin_lock_init(&vif->hash.cache.lock);
	INIT_LIST_HEAD(&vif->hash.cache.list);
}

void xenvif_deinit_hash(struct xenvif *vif)
{
	xenvif_flush_hash(vif);
}